Colecovision won't power on - help?

I have a Colecovision that won't power on. No black screen, no BIOS screen, nada.

I've verified via multimeter that the power supply seems to have 12, 5, and -5 volts where it should, including where it connects to the board, but when I switch the power on, the 5 volt reading jumps down to 1.6.

Is this an expected drop, or an indication that I've got a bad power supply?

Wait! You said the power supply was putting out the correct voltages. How did just changing to a new power supply fix the issue if the one you were using to begin with was working? I am having the same issue but only have one power supply. I have two Colecovisions and neither power up at all. I test the power supply and the voltages are correct but get nothing from the Colecos.

If the power supply has a bad regulator, it can still read correct voltage with no load, but fail under load.

As someone mentioned though, the board will have a characteristic DC resistance to ground on the +5V rail. On mine (rev J) it will be about 72 ohms. Any less than that, and you might have a component drawing too much power, which can also lead to power supply failure.

Hi, would please explain the process of doing this measurement? I just want to be completely sure I will do it correctly when needed. I have come accross a couple of CV consoles that appear to draw too much power. I thought it was a component is short or failing but I did not know how to best identify it. Thanks a lot! Al

The easy way is to unplug the CV, turn it on, open the expansion port, and check the resistance between the two large contacts on the left side (one on top, one on bottom). On my board that reads about 75 ohms.